Electric-field-induced interlayer hybridization and switching in bilayer PtTe2 field-effect transistors

Two-dimensional (2D) transition metal dichalcogenides (TMDs) offer a versatile platform for band-structure engineering and nanoelectronic device design. Among them, bilayer PtTe 2 resides at the boundary between metallic and semiconducting behavior, providing a unique opportunity for electrically controlled phase modulation. Here, we show that a perpendicular electric field opens a bandgap in bilayer PtTe 2 and modulates interlayer coupling, making an expanded semiconducting configuration energetically favorable relative to the equilibrium metallic state. Density functional theory calculations combined with electric-field-dependent nudged elastic band analysis reveal that a perpendicular field of 2.5 MV/cm shifts the interlayer energy landscape and stabilizes a semiconducting configuration with a bandgap of ∼0.44 eV. Non-equilibrium Green’s function transport simulations reveal that this field-control interlayer modulation simultaneously induces (i) bandgap opening, (ii) modification of band-edge curvature and effective mass, (iii) enhanced electrostatic carrier depletion, and (iv) an evolution from effectively ohmic-like carrier injection in the metallic ON state to increasingly barrier-limited injection in the semiconducting OFF state. These mechanisms explain the coexistence of a relatively steep subthreshold swing and a large ON/OFF current ratio, while preserving metallic transport in the ON regime. The device remains within the thermionic regime, improving the practical steep-slope trade-off between switching efficiency and ON-state current rather than surpassing the Boltzmann limit. These findings identify field-controlled interlayer modulation in bilayer PtTe 2 as a promising mechanism for improving the balance between switching efficiency and ON-state conductivity in nanoscale electronic devices.